The valve, which forms the subject of the invention, is of the sort of those which include a valve body intended to be fixed into a dished part, closing the container, with the interposition of a sealing washer between an open front end of the valve body and the dished part, and a control stem able to slide in the valve body between a position of rest and an open position. The valve body forms a chamber, which is isolated from the outside when the stem is at rest and interacts with the sealing washer so as to close the chamber. The stem is held in this position of rest by elastic return means. An additional gas inlet orifice is provided in the lateral wall of the valve body, which body is equipped, at its lower part, with a means for fastening the flexible pocket containing the liquid.
FR-A-2,415,250 shows a valve of this sort for dispensing, with mixing, two products contained respectively in a flexible pocket and in a container surrounding the pocket. The mixing of the products to be dispensed takes place in a chamber, which is located in a pushbutton surmounting the valve. The design is relatively complicated.
Moreover, U.S. Pat. No. 3,283,962 discloses a three-position valve for an aerosol container in which the liquid to be sprayed is directly in contact with the propellent gas, without being enclosed within a flexible pocket. A gas inlet orifice is provided in the wall of the chamber of the valve body; however, when the stem is in the dispensing position, this orifice is closed by a collar integral with the stem.
There has also been proposed, especially in DE-A-1,812,718, a valve for dispensing, in the form of a spray, a liquid contained in a flexible pocket the valve being as defined previously and one which, while making it possible to mix the liquid and the propellent gas in the chamber of the valve body, makes it possible to prevent pressurized gas from the container from entering the flexible pocket containing the liquid. The valve also prevents liquid from flowing out towards the container. The arrangement of such a valve offers the advantage of allowing the container equipped therewith to be used in all positions but, unfortunately, does not allow the chamber of the valve body to be purged each time, before and after a dose of a liquid/gas mixture is dispensed.
The object of the present invention is to propose a valve which does not exhibit these drawbacks.